Ultrasonic horn for removal of hard tissue

ABSTRACT

Ultrasonic horns configured for use with a surgical ultrasonic handpiece including a resonator are described. The ultrasonic horns include an elongated member having a longitudinal internal channel extending partially therethrough. Disposed on the distal end of the elongated member is a chisel and awl shaped tip configured for cutting and/or abrading hard tissue, for example bone.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to, U.S. Provisional Patent ApplicationSer. No. 60/671,739 entitled Ultrasonic Horns, filed Apr. 15, 2005, theentirety of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

This disclosure relates to surgical systems and, more particularly, toultrasonic horns for fragmenting tissue during a surgical procedure.

2. Background of Related Art

Devices which effectively utilize ultrasonic energy for a variety ofapplications are well-known in a number of diverse arts. The Ampulla(Gaussian) profile was published by Kleesattel (as early as 1962), andis employed as a basis for many ultrasonic horns in surgicalapplications including devices patented and commercialized by Cavitronand Valleylab (patents by Wuchinich, et al, 1977, Stoddard, et al, 2001)for use in ultrasonic aspiration. The Gaussian profile is used inpractice to establish and control the resonance and mechanical gain ofhorns. A resonator, a connecting body and the horn act together as athree-body system to provide a mechanical gain, which is defined as theratio of output stroke amplitude of the radiating tip to the inputamplitude of the resonator. The mechanical gain is the result of thestrain induced in the materials of which the resonator, the connectingbody and the ultrasonic horn are composed. The magnetostrictivetransducer coupled with the connecting body functions as the first stageof the booster horn with a mechanical gain of about 2:1.

The magnetostrictive transducer coupled with the connecting bodyfunctions as the first stage of the booster horn with a mechanical gainof about 2:1, due to the reduction in area ratio of the wall of thecomplex geometry. The major diameter of the horn transitions to thelarge diameter of the Gaussian in a stepped horn geometry with a gain ofas large as about 5:1, again due to reduction in area ratio. Themechanical gain increases in the Gaussian due to the Square Root of(1+2*Ln (Area Ratio)), where Ln is the natural logarithm, or about 2:1for the horns of interest. The total mechanical gain is the product ofthese constituents, or as large as 20:1 for this example. Thus, theapplication of ultrasonically vibrating surgical devices used tofragment and remove unwanted tissue with significant precision andsafety has led to the development of a number of valuable surgicalprocedures. Accordingly, the use of ultrasonic aspirators for thefragmentation and surgical removal of tissue from a body has becomeknown. Initially, the technique of surgical aspiration was applied forthe fragmentation and removal of cataract tissue. Later, such techniqueswere applied with significant success to neurosurgery and other surgicalspecialties where the application of ultrasonic technology through ahandheld device for selectively removing tissue on a layer-by-layerbasis with precise control has proven feasible.

Certain devices known in the art characteristically produce continuousvibrations having substantially constant amplitude at a predeterminedfrequency (i.e. 20-30 kHz). Certain limitations have emerged in attemptsto use such devices in a broad spectrum of surgical procedures. Forexample, the action of a continuously vibrating tip may not have adesired effect in breaking up certain types of body tissue, bone, etc.Because the ultrasonic frequency is limited by the physicalcharacteristics of the handheld device, only the motion available at thetip provides the needed motion to break up a particular tissue. Allinteraction with the tissue is at the tip, some is purely mechanical andsome is ultrasonic. Some teach in the art that interaction with thetissue at the tip lead is due only to mechanical interaction. In anycase, the devices have limitations in fragmenting some tissues. Thelimited focus of such a device may render it ineffective for certainapplications due to the vibrations which may be provided by the handhelddevice. For certain medical procedures, it may be necessary to usemultiple hand held devices or it may be necessary to use the sameconsole for powering different handheld devices.

Certain devices known in the art characteristically produce continuousvibrations having a substantially constant amplitude at a frequency ofabout twenty to about thirty kHz up to about forty to about fifty kHz.The amplitude is inversely proportional to frequency and directlyproportional to wavelength because the higher frequency transducersgenerally have less powerful resonators. For example, U.S. Pat. Nos.4,063,557, 4,223,676 and 4,425,115 disclose devices suitable for theremoval of soft tissue which are particularly adapted for removinghighly compliant elastic tissue mixed with blood. Such devices areadapted to be continuously operated when the surgeon wishes to fragmentand remove tissue, and generally is operated by a foot switch.

A known instrument for the ultrasonic fragmentation of tissue at anoperation site and aspiration of the tissue particles and fluid awayfrom the site is the CUSA™ 200 System Ultrasonic Aspirator manufacturedand sold by Radionics, Inc. of Burlington, Mass., a subsidiary of TycoHealthcare Group LP; see also U.S. Pat. No. 4,827,911, now sold byRadionics, Inc. as the CUSA EXcel™. When the longitudinally vibratingtip in such an aspirator is brought into contact with tissue, it gently,selectively and precisely fragments and removes the tissue. Depending onthe reserve power of the transducer, the CUSA™ transducer amplitude canbe adjusted independently of the frequency. In simple harmonic motiondevices, the frequency is independent of amplitude. Advantages of thisunique surgical instrument include minimal damage to healthy tissue in atumor removal procedure, skeletoning of blood vessels, prompt healing oftissue, minimal heating or tearing of margins of surrounding tissue,minimal pulling of healthy tissue, and excellent tactile feedback forselectively controlled tissue fragmentation and removal.

In many surgical procedures where ultrasonic fragmentation instrumentsare employed, additional instruments are required for tissue cutting andhemostasis at the operation site. For example, hemostasis is needed indesiccation techniques for deep coagulation to dry out large volumes oftissue and also in fulguration techniques for spray coagulation to dryout the surface of tissues.

The apparatus disclosed in U.S. Pat. Nos. 4,931,047 and 5,015,227provide hemostasis in combination with an ultrasonically vibratingsurgical fragmentation instrument and aspirator. The apparatuseffectively provide both a coagulation capability and an enhancedability to fragment and aspirate tissue in a manner which reduces traumato surrounding tissue.

U.S. Pat. No. 4,750,488 and its two continuation U.S. Pat. Nos.4,750,901 and 4,922,902 disclose methods and apparatus which utilize acombination of ultrasonic fragmentation, aspiration and cauterization.

In an apparatus which fragments tissue by the ultrasonic vibration of atool tip, it is desirable, for optimum efficiency and energyutilization, that the transducer which provides the ultrasonic vibrationoperate at resonant frequency. The transducer design establishes theresonant frequency of the system, while the generator tracks theresonant frequency. The generator produces the electrical driving signalto vibrate the transducer at resonant frequency. However, changes inoperational parameters, such as changes in temperature, thermalexpansion and load impedance, result in deviations in the resonantfrequency. Accordingly, controlled changes in the frequency of thedriving signal are required to track the resonant frequency. This iscontrolled automatically in the generator.

During surgery, fragmentation devices, such as the handpieces describedabove, are used internally to a patient. A surgeon manipulates thehandpiece manually at an operative site, and therefore, the handpieceitself may reduce visibility of the operative site. It would thereforebe advantageous to provide an apparatus with the above-describedfeatures with a smaller profile such that a greater field of view isprovided for the surgeon at the operative site.

Emergent requirements for ultrasonic surgical devices include removal ofmore tenacious brain tumors with calcified or fibrous tissues, cuttingor abrading bone encountered given the evolution of transsphenoidal orendoscopic surgical approaches to deeper regions of the brain, andextending openings in bony cavities or sectioning bone to revealunderlying surgical sites with greater control than afforded by existingmanual or motorized tissue cutting instruments. Improved approaches tosurgery on the spine and orthopedic applications often require cuttingor abrading bone for “opening” surgical sites, sculpting, and creatingnotches, grooves, and blind holes. Inherent in the emergent requirementsis the need to protect the critical anatomy (e.g., the carotid artery,optical nerve, other nerves, and glands) in proximity to portions of theinstrument while it is inserted and operated. The evolving surgicalapproaches require the transmission of cutting and abrasion powerthrough small openings, with space shared by endoscopes or the necessaryvisual field of microscopes, and other surgical instruments (e.g.,suction devices, coagulators, etc.).

SUMMARY OF THE INVENTION

In accordance with the present invention an ultrasonic horn has anAmpulla (Gaussian) to inverse exponential to chisel/awl distal endprofile which affords mechanical gain and propagation of ultrasound withminimal errant reflection and standing waves that could limittransmitted sound and reduce horn stroke amplitude.

In one aspect of the present invention, an ultrasonic horn is providedwith quiescent power that is similar to ultrasonic aspiration horns thatdo not have solid distal ends.

In another aspect of the present invention, an ultrasonic horn isprovided with reserve power that is far greater than is needed toreadily cut or abrade bone.

In yet another aspect of the present invention, an ultrasonic horn isprovided which can be utilized to remove very fine layers of bone with achisel, in monolayers or planes.

In still one other aspect of the present invention, an ultrasonic hornis provided having fine control characteristics typically exhibited byultrasonic abrasive devices with file-like structures, while bettersupporting defined cutting or abrasion of sections, planes, notches,grooves, and holes in bone.

In one aspect of the present invention, an ultrasonic horn is providedwith a profile that affords superior bulk removal of bone as compared toexisting ultrasonic devices.

In yet one other aspect of the present invention, an ultrasonic horn isprovided with a blunt or dull chisel/awl distal end or tip which is morecone-like with a monotonically increasing diameter, thereby improvingsafety in insertion, and requiring minimal space.

Still another aspect of the invention is an ultrasonic horn which can beoptionally operated such that the concentrated ultrasound afforded withthe chisel/awl distal end results in cavitation, the latter aiding incutting and abrading bone.

Yet another aspect of the invention is an ultrasonic horn which, in viewof existing manually spring-activated surgical instruments used inopening or extending bony cavities such as the sinus bone cavity has achisel and awl distal end to afford improved control to reduce thelikelihood of unpredictable fracturing which may result in severebleeding.

One aspect of the invention is an ultrasonic horn configured for usewith a surgical ultrasonic handpiece having a resonator that generatesan ultrasonic wave. The ultrasonic horn includes a tapered elongatedmember having a proximal end, a distal end, an intermediate point, and acentral longitudinal axis. An adapter is disposed on the proximal end ofthe elongated member. A tip lead is configured on the distal end of theelongated member. The tip lead is configured for cutting hard tissue andhas a chisel and awl shaped distal end. The tip lead has a chisel anglethat is bisected by the central longitudinal axis of the elongatedmember. The tip lead may have blunt edges, a first planar surface, andan opposing second surface. An internal channel is disposed within theelongated member and the adapter. The internal channel forms a hollowlength extending from the intermediate point in the elongated member tothe proximal end of the elongated member. The internal channel mayfurther extend through the adapter. In at least one aspect of theinvention, the internal channel may have a substantially constantdiameter and is disposed longitudinally and centrally in the elongatedmember.

In yet another aspect of the present invention, the first planar surfaceof the tip lead has an abrasive mill-file configuration. In stillanother aspect of the invention, the elongated member is a completelysolid mass from the intermediate point to the distal end. In yet anotheraspect of the invention, the first planar surface of the tip lead has acurvilinear edge.

In one aspect of the present invention, the ultrasonic horn includes anadapter having a distal end and proximal end configured to connect withan ultrasonic resonator. A shaft extends from the proximal end of theadapter. A connecting member is disposed between the proximal end andthe distal end of the adapter. A flange having a leading edge isdisposed on the distal end of the adapter.

In still another aspect of the invention, the ultrasonic horn furtherincludes a connecting portion. The connecting portion may be configuredto couple with the resonator. In yet another aspect of the presentinvention, the ultrasonic horn is configured to operate at a targetfrequency of about 23 kHz. In still another aspect of the presentinvention, the ultrasonic horn is configured to operate at a targetfrequency of about 36 kHz. The ultrasonic horn may be made from a metal,for example, stainless steel or titanium.

In one additional aspect of the present invention, the ultrasonic wavegenerated by the resonator has at least one node and at least oneantinode. The proximal end of the adapter is disposed near the at leastone node of the ultrasound wave and the tip lead is disposed near the atleast one antinode of the ultrasound wave.

In still one other aspect of the invention, the distal end of theelongated member is a completely solid mass having an inverseexponential profile from the intermediate point to the distal end of theelongated member. The proximal hollow length of the elongated member hasa Gaussian profile.

In another aspect of the invention, the ultrasonic horn further includesan extension member and a flared member disposed between the adapter andthe elongated member. The extension member and the flared member includean extension of the internal channel. In accordance with the presentinvention, the ultrasonic horn may be configured to operate at a targetfrequency of about 36 kHz. In one aspect of the invention, theultrasonic horn may be configured to operate at a target frequency ofabout 23 kHz.

Still another aspect of the present invention is an ultrasonic hornconfigured for use with a surgical ultrasonic handpiece having aresonator which generates an ultrasonic wave. The ultrasonic hornincludes a tapered elongated member having a proximal end, a distal end,an intermediate point, and a central longitudinal axis. The ultrasonichorn may have an adapter disposed on the proximal end. An internalchannel is disposed longitudinally within the elongated member and theadapter. The internal channel forms a hollow length extending from theintermediate point in the elongated member to the proximal end of theelongated member. The internal channel further extends through theadapter. The internal channel may terminate before the resonator. Theelongated member may be a completely solid mass from the intermediatepoint to the distal end. A tip lead is configured on the distal end ofthe elongated member. The tip lead is adapted for cutting hard tissue.The tip lead may have blunt edges, a generally blunt distal tip, a firstplanar surface having an abrasive mill-file configuration, and anopposing second surface that follows the contour of a distal solidportion of the elongated member. In yet another aspect, the first planarsurface has a curvilinear edge.

In yet another aspect of the present invention, the adapter includes adistal end and a proximal end configured to connect with an ultrasonicresonator. A shaft extends from the proximal end of the adapter. Aconnecting member may be disposed between the proximal end and thedistal end. A flange having a leading edge may be disposed on the distalend of the adapter. The ultrasonic horn may further include a connectingportion. The connecting portion is configured to couple with theresonator.

In one aspect of the invention, the internal channel of the ultrasonichorn has a substantially constant diameter. The internal channel isdisposed longitudinally and centrally in the elongated member.

Other features and advantages of the present invention will become moreapparent from the following detailed description of the invention, whentaken in conjunction with the accompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the presently disclosed ultrasonic horn are describedherein with reference to the drawings, wherein:

FIG. 1A is a perspective view of an ultrasonic horn in accordance withan embodiment of the present disclosure;

FIG. 1B is an enlarged view of a tip of the ultrasonic horn of FIG. 1A;

FIG. 2 is a longitudinal cross-sectional view of the ultrasonic horn ofFIG. 1A together with a resonator for activating the ultrasonic horn;

FIG. 3 is a top view of the ultrasonic horn of FIG. 1A with a channelshown in phantom;

FIG. 4 is a side view of the ultrasonic horn of FIG. 1A;

FIG. 5 is a cross-sectional view of the ultrasonic surgical horn of FIG.3;

FIG. 6 is a cross-sectional view of the ultrasonic surgical horn of FIG.4;

FIG. 7 is a graph of the ultrasonic horn radius versus horn length for atarget frequency of 23 kHz;

FIG. 8 is a cross-sectional view of a portion of the ultrasonic hornaccording to FIG. 7 showing a Gaussian profile;

FIG. 9 is another graph of the ultrasonic horn radius versus horn lengthas illustrated in FIG. 7;

FIG. 10A is a perspective view of an ultrasonic horn in accordance withanother embodiment of the present disclosure;

FIG. 10B is an enlarged view of a tip of the ultrasonic horn of FIG.10A;

FIG. 11 is a top view of the ultrasonic horn of FIG. 10A with a channelshown in phantom;

FIG. 12 is a side view of the ultrasonic horn of FIG. 10A;

FIG. 13 is a cross-sectional view of the ultrasonic surgical horn ofFIG. 11;

FIG. 14 is a cross-sectional view of the ultrasonic surgical horn ofFIG. 12;

FIG. 15 illustrates the cross-sectional view of a portion of theultrasonic horn of FIG. 8 showing a Gaussian profile together with atable illustrating sample modeling data and results from severalultrasonic horns that were fabricated according to an embodiment of thepresent disclosure;

FIG. 16 is a table of experimental data comparing parameters of anultrasonic horn according to the present disclosure to parameters of anultrasonic horn of the prior art.

FIG. 17 is a cross-sectional view of the ultrasonic horn of FIGS. 1A, 1Bthrough FIG. 6 showing node and antinode locations corresponding to theexperimental data of FIG. 16;

FIG. 18 is a partial perspective view of an ultrasonic horn inaccordance with yet another embodiment of the present disclosure;

FIG. 19 is a cross-sectional view of the ultrasonic horn of FIG. 17together with a resonator for activating the ultrasonic horn;

FIG. 20 is a top view of the ultrasonic horn of FIG. 17 with a channelshown in phantom;

FIG. 21 is a partial perspective view of an ultrasonic horn inaccordance with still another embodiment of the present disclosure;

FIG. 22 is a profile view of the ultrasonic horn of FIG. 21 furtherhaving an extension member and showing node and antinode locationsresulting from an experimental analysis analogous to that which resultedin the experimental data of FIG. 16;

FIG. 23 is a partial perspective view of an ultrasonic horn inaccordance with still yet another embodiment of the present disclosure;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the presently disclosed ultrasonic horn will now bedescribed in detail with reference to the drawings, in which likereference numerals designate identical or corresponding elements in eachof the several views. As used herein, the term “distal” refers to thatportion of the instrument, or component thereof which is further fromthe user while the term “proximal” refers to that portion of theinstrument or component thereof which is closer to the user.

An ultrasonic horn 100, in accordance with one embodiment of the presentdisclosure, is illustrated in FIG. 1A. Ultrasonic horn 100 is adaptedfor use in an ultrasonic surgical system having an ultrasonic handpiece.An example of such an ultrasonic surgical system is disclosed in U.S.Pat. No. 6,214,017 to Stoddard et al. currently owned by and assigned toSherwood Services AG, the entire contents of which are incorporatedherein by reference. Alternatively, ultrasonic horn 100 may be adaptedfor use with the ultrasonic surgical system disclosed in U.S. Pat. No.4,063,557 to Wuchinich et al., the entire contents of which areincorporated herein by reference.

Referring to FIGS. 1A, 1B, and 2, in one embodiment of the presentdisclosure, ultrasonic horn 100 includes an adapter 130 having a firstor proximal end 172 and a second or distal end 174. Adapter 130includes, extending from proximal end 172, a shaft 132, a threadedmember 134 and a flange 136 terminating at distal end 174. Flange 136includes a leading edge 138. Proximal end 172 of adapter 130 isconfigured to connect ultrasonic horn 100 to an ultrasonic handpiece orresonator 150 via a connecting portion 140. Connecting portion 140 iscapable of coupling ultrasonic horn 100 and connecting portion 140 toultrasonic handpiece or resonator 150. As used herein, the termresonator is used to refer to what is often referred to in theliterature as an ultrasonic handpiece. Those skilled in the art willrecognize that threaded member 134 is identified herein in oneembodiment as an externally threaded member for connection to aninternally threaded connecting body and/or to an ultrasonic resonator(not shown) but that other connection types can be implemented toconnect to the connecting body and/or ultrasonic resonator. Suchconnection types include but are not limited to welds, socket couplings,and compression couplings.

Ultrasonic horn 100 includes an elongated member 110 having a first orproximal end which coincides with distal end 174 of adapter 130.Elongated member 110 has a second or distal end 180, and distal end 174of adapter 130 is joined, in one embodiment unitarily, to the coincidingproximal end of elongated member 110. Distal end 180 of elongated member110 is configured as a tip lead 120. Tip lead 120 extends from a firstor proximal end, as is discussed in more detail below.

Connecting portion 140 includes a first or proximal end 142 which isconfigured to connect to a resonator 150 at a distal end. Resonator 150includes, in one embodiment, a magnetostrictive transducer, althoughother transducer types can be included such as a piezoelectrictransducer. Resonator 150 is supplied power from a generator (not shown)such that resonator 150 operates at a desired frequency, e.g., in therange of about 23,000 Hz (23 kHz). In one embodiment, ultrasonic horn100 is made of titanium, although other materials such as stainlesssteel may be used.

As best seen in FIG. 2, which is a longitudinal cross-sectional view ofthe ultrasonic horn of FIG. 1A, an internal channel 160 is formed withinelongated member 110 and extends into connecting body 140, where itterminates before resonator 150. As is known in the art, the channelterminates in the connecting body, and does not continue in theresonator. The resonator is typically a laminated core-stack ofPermanickel. In most implementations, the central channel supportsaspiration or suction of tissue. The channel also affords greatermechanical gain because the gain is dependent on the reduction in arearatio of the thin walls. The primary purpose of the channel is tosupport gain for bone tips with the chisel/awl distal ends. The internalchannels of the bone abrading tips in the disclosure shown and describedbelow would also aid in cooling, where irrigation liquid is suctionedvia the internal diameter channel. Surgical procedures on bone typicallyemploy an auxiliary suction tube to remove the larger volumes ofirrigation liquid and bone debris.

Referring to FIGS. 3-6, FIG. 3 is a top view of ultrasonic horn 100 ofFIG. 1A with channel 160 shown in phantom formed within elongated member110. FIG. 4 is a side view of ultrasonic horn 100 of FIG. 1A withchannel 160 in phantom formed within elongated member 110. FIG. 5 is across-sectional view of ultrasonic surgical horn 100 of FIG. 3 showingchannel 160 formed within elongated member 110. FIG. 6 is across-sectional view of ultrasonic surgical horn 100 of FIG. 4 againshowing channel 160 formed within elongated member 110. Internal channel160 is formed within adapter 130 and elongated member 110 of ultrasonichorn 100.

Elongated member 110 is tapered such that the cross-sectional area is amaximum at proximal end 174 interfacing with adapter 130 and is aminimum at proximal end 178 of tip lead 120. Channel 160 is asubstantially constant diameter central hole of diameter d₁ formedwithin elongated member 110 to enable enhanced mechanical gain in horn100. As will be explained in more detail below with respect to FIG. 8,an area function is defined as N where N=Sgo/Sc is the area ratio of theGaussian portion, and it establishes gain as described in the remarksentered above. In the case of a horn with a channel, it is the arearatio of the cross-sectional area based on the outer diameter of theelongated member 110 near the leading edge 138 of flange 136 versus thecross-sectional area based on the outer diameter of the elongated member110 at the distal end 176. The area ratio along the length L of the hornis decreasing towards tip lead 120 at the distal end of elongated member110, and velocity and elongation of the titanium particles areincreasing. The ultrasonic wave is supported by particle motion in thetitanium. The particles are vibrating about their neutral position in alongitudinal or extensional wave. The particles do not move along thelength of the horn, but only vibrate, just as a cork or bobber showsthat a wave passes through water via the liquid. As the horn wallthickness decreases, more strain occurs in the metal as the particlesmove a greater distance about their neutral position. The displacementof the end of the horn is due to strain along the horn. All theparticles supporting the wave are moving at the same resonant frequency.The greater the strain, the greater the velocity of the particlesnecessary to maintain the same frequency

As illustrated in FIGS. 3-6, several dimensions are identified that formthe basis for achieving a desired target frequency of about 23 kHz forultrasonic horn 100. More particularly, L6 is the length of shaft 132and threaded member 134 from proximal end 172 of adapter 130 to leadingedge 138 of flange 136. L1 is the length of adapter 130 from leadingedge 138 of flange 136 to distal end 174 thereof.

As will be explained in more detail below, L2 is the length of a hollowportion 112 of channel 160 formed in elongated member 110 whose outerradius R is formed according to a normal, also referred to as a Gaussianprofile distribution. Length L2 extends from the second or distal end174 of adapter 130, which coincides with the first or proximal end ofelongated member 110, approximately to an intermediate point 176coinciding with the distal end of channel or central hole 160 withinelongated member 110. Therefore, the length defined by the sum of L1 andL2 defines the length Lg of the Gaussian profile distribution, orLg=L1+L2. A portion 184 of the ultrasonic horn 100 is defined by thelength Lg of the Gaussian profile distribution. The approximate lengthof channel 160 within elongated member 110 is length L2. Therefore,channel 160 extends a predetermined distance equal to sum of L6 and L1and L2 from proximal end 172 of adapter 130 to intermediate point 176within elongated member 110 between proximal and distal 174 and 180,respectively, of elongated member 110. In addition, channel 160 therebyhas an open end at proximal end 172 of the adapter and a closed end atthe intermediate point 176 within elongated member 110.

Dimension L3 is the length of a solid portion 114 of elongated member110 whose radius R is formed according to an inverse exponential profiledistribution. Length L3 of solid portion 114 of elongated member 110extends from approximately second or distal end 176 of channel orcentral hole 160 to first or proximal end 178 of elongated member 110 attip lead 120. Dimension L4 corresponds to the length of tip lead 120 andis the length of a solid portion 116 of elongated member 110 extendingfrom first end 178 of elongated member 110 at tip lead 120 to distal end180 of elongated member 110. Elongated member 110 is thereby acompletely solid mass from intermediate point 176 to distal end 180.Therefore, tip lead 120 extends from first or proximal end 178 to secondor distal end 180 of elongated member 110. Radius R, or more correctly,height Y, of tip lead 120 is formed according to a tangential or linearprofile distribution. L5 is the total length of ultrasonic horn 100extending from leading edge 138 of flange 136 to second or distal end180 of elongated member 110 and is equal to the sum of L1, L2, L3 andL4. Length L5=L1+L2+L3+L4 is referred to herein, in accordance with theterminology conventional in the art, as the length of the tip, L_(tip),of ultrasonic horn 100. That is, tip 190 is defined as the portion ofultrasonic horn 100 extending distally from leading edge 138 of flange136 to distal end 180. Therefore, L_(tip)=L5. When ultrasonic horn 100is connected to connecting portion 140, channel 160 extends throughconnecting portion 140 and terminates before resonator 150. A portion186 of ultrasonic horn 100 is defined by sum L_(c) of lengths L3+L4.Portion 186 extends distally from intermediate point 176 to distal end180.

As best illustrated in FIG. 1B, distal end 180 of tip lead 120 has asemi-circular planar surface configuration 122, such that distal end 180of ultrasonic horn 100 is in the form of a chisel and an awl. Asdiscussed below, very tip 180 of ultrasonic horn 100 is blunt or dull.The boring of holes with horn 100 is better facilitated with slightlysemi-circular manual motion; however plunge cuts in bone and wood havebeen accomplished with just longitudinal motion of horn 100. Thecombination of the chisel and awl distal end 180 of horn 100 supportsdefined cutting or abrasion of sections, planes, notches, grooves, andholes in bone.

Channel or central hole 160 extends from proximal end 172 of adapter 130to approximately distal end 176 of channel 160, which coincides withproximal end of solid portion 114 of elongated member 110. In oneembodiment of the present disclosure, as illustrated in FIGS. 7 and 8,the outer radius R(x) of elongated member 110 along hollow portion 112is formed according to a Gaussian distribution, as given by thefollowing Equations (1), (2), (3), (4), (5), (6), (7) and (8).S _(g)(x)=S _(gO) e ^(−1/2(ω) _(i)/^(Cg)2×2)  (1)ω_(i) ={Cg/L _(tip)}{arctan(1/[2 ln(N)]^(1/2))+[2 ln(N)]^(1/2)}  (2)f_(i)ω_(i)/2π  (3)N=S _(gO) /S _(c)  (4)R(x)={S _(g)(x)/π}^(1/2)  (5)S _(c) =π{D _(c)/2}^(1/2)  (6)S _(gO) =π{D _(gO)/2}²  (7)C _(g) =[E _(g)/ρ]^(1/2)  (8)where:

x is the distance along the length of the central longitudinal axis A ofelongated member 110, with x=0 coinciding with the leading edge 138 offlange 136;

C_(g) is the speed of sound in the metal, in inches/sec, E_(g) is theelastic modulus (or Young's modulus) in lbf/inch², and p is the densityof the metal in lbm-sec²/inch⁴. For this application, the metal istitanium, so that E_(g) is about 16,500,000 lbf/inch² and ρ is about0.0004147 lbm-sec²/inch⁴ Therefore, C_(g) equals about 199,470 inchesper sec.

D_(c) is the outer diameter {2×|R(x)|} of elongated member 110 at distalend 176 of channel 160, in inches;

D_(gO) is the outer diameter {2×|R(x)|} of elongated member 110 nearleading edge 138 of flange 136. The major diameter of the calculatedGaussian portion 184 lies under the radius of curvature, R_(cv) of theflange 136, as shown in FIG. 3.

S_(c) is the total cross-sectional area of elongated member 110 atdistal end 176 of channel 160, in square inches (see FIG. 9);

S_(gO) is the total cross-sectional area of elongated member 110 alonghollow portion 112 which varies as a function of x, in square inches(see FIG. 9);

N is the ratio of S_(gO)/S_(c), a dimensionless number;

f_(i) is the designed resonant frequency of horn 100 which consists ofthe Gaussian portion represented by the length Lg=L1+L2 plus theremaining length L_(c)=L3+L4 through to distal end 180 of tip 190, andthis resonant frequency is consistent with the combination of resonator150, connecting body 140, and ultrasonic horn 100, in Hz or cycles/sec.

ω_(i) is the angular frequency of resonator 150, connecting body 140,and ultrasonic horn 100, in rad/sec, at resonant frequency f_(i);

C_(g) is the acoustic velocity, in in/sec; and

L_(tip) is length L₅ of tip 190, in inches.

As noted previously, L_(tip), is composed of length L_(g) of theGaussian portion 184 plus the length of the remaining horn from distalend 176 of channel 160 to distal end 180 of the ultrasonic horn 100.

The designed angular frequency of the horn, ω_(i) in radians/sec, isdetermined by equation (2). The N value is the area ratio of Gaussian.L_(tip), is composed of length L_(g) of Gaussian portion 184 plus lengthL_(c) of portion 186 of ultrasonic horn 100 defined by sum L_(c) oflengths L3+L4. Portion 186 extends distally from intermediate point 176to distal end 180.

Gaussian portion 184 contributes the [2 ln(N)]^(1/2) portion of theequation, and the remaining length L_(c) represented by portion 186 isapproximated by the arcTan of the inverse of [2 ln(N)]^(1/2). It shouldbe noted that the angular frequency ω_(i) is controlled by area ratio N,as given by equations (4), (6) and (7), and the length of tip L_(tip) inthe divisor, and the speed of sound in titanium C_(g) is a materialproperty.

The wavelength λ is defined as C_(g)/f_(i) and L_(tip)=λ/4. Length ofresonator 150 is about λ/2, the length of connecting body 140 is aboutλ/4, and length L_(tip) of horn 100 is about λ/4, and these summing toone full wavelength. These are not ideal dimensions due to complexgeometries, and because resonance modes at frequencies other than at 23kHz exist.

It should be noted that the dimensions do not yield a unique solutionbecause the frequency f_(i) is dependent on the diameters D_(gO) andD_(c) of Gaussian portion 184 and length L_(tip). A shorter or longerlength L_(tip) could be selected, and diameters D_(gO) and D_(c)adjusted to again attain required frequency f_(i). These distance anddiameter parameters can be adjusted without fundamentally deviating fromthe Gaussian-decaying exponential-tangent function profile of a chiselawl distal end.

L_(c) parameter is the length (L₃ and L₄) of horn 100 remaining afterGaussian portion 184. L_(g) parameter is the length of Gaussian portion184. L_(g) is the dimension of the length from the end of Gaussianportion 184 or its small diameter D_(c) to large diameter D_(go) ofGaussian portion 184. The larger diameters of Gaussian portion 184actually lie under structure, such as the shaft 132, threaded member134, and flange 136. It is not practical to mathematically model thiscomplex structure. Physical dimension of L_(g) is the distance from thebeginning of the major diameter of the flange, i.e., leading edge 138 offlange 136, which mates with connecting body 140 and extends distally tointermediate point 176.

To provide tip lead 120 of elongated member 110 with a shapeapproximating a point of a chisel and awl at distal end 180, solidportion 114 of elongated member 110 is formed with a profile having anouter radius R(x) according to an inverse exponential function as givenby the following equation:R(x)={D _(c)/2}{e ^(−(1/2)x)}  (9)where again D_(c) is outer diameter {2×|R(x)|} of elongated member 110at distal end 176 of channel 160, which coincides with proximal end ofsolid portion 114, in inches. The exponential decay parameter ½ isuniquely selected to precisely transition from the Gaussian distributionat distal end 176 of channel 160.

As an example, in one embodiment of horn 100, function e^(−(1/2)x) canbe used. To visualize the profiles in view of the comparatively narrowaspect ratio, (R(x)/x), of actual horn 110, y axis indicating R(x) ismagnified in FIG. 7. Central hole 160 is not shown on the graph in FIG.7. The area function N of the Gaussian distribution of Equation (1)influences resonant frequency f_(i) and the mechanical gain. Totallength L5 of ultrasonic horn 100 is set at λ/4 according to acousticwavelength λ at resonant frequency f_(i). As indicated by Stoddard etal., in U.S. Pat. No. 6,214,017 B1, in one embodiment, the lengths ofresonator stack 150, connecting portion 140 and ultrasonic horn 100 areλ/2, λ/4, and λ/4, respectively. Therefore, length of resonator 150 plusthe length of connecting body 140 plus the length of ultrasonic horn 100equals λ. The mechanical gain is defined herein as the ratio of theoutput stroke of the ultrasonic horn at distal end 180 of tip lead 120to the input stroke at the proximal end of resonator 150. Mechanicalgain occurs anywhere there is a change in cross-sectional area of theassembly of resonator 150, connecting body 140 and ultrasonic horn 100.The positions where there is a change in cross-sectional area are forexample distal end 174 of adapter 130, distal end 176 of channel 160,and distal end 178 of solid portion 114 of elongated member 110 whichinterfaces with proximal end of tip lead 120. At resonant frequency,those positions become the locations of nodes and antinodes of acousticwavelength λ. In particular, since an antinode is a point of maximumdisplacement, tip lead 120 is therefore near an antinode. Since a nodeis a point of minimum displacement, proximal end 172 of adapter 130 isnear a node. Therefore, proximal end 172 of adapter 130 intersects anode of a generated ultrasonic wave and tip lead 120 at second end 180of elongated member 110 intersects an anti-node of the generatedultrasonic wave. The absolute positions of the nodes and antinodes arenot exact because the geometry is quite complex, i.e., the geometry doesnot consist simply of bars, rods, Gaussian, exponential, etc. Actualfinite element analysis modeling, using programs such as PRO/Mechanica(by PTC of Needham, Mass., USA), of the entire geometry complements thesimple mathematical model shown in FIG. 7. The simple mathematical modeldoes illustrate the need for proper selection of the horn geometry.Again, the inverse exponential distribution profile of Equation (9) isselected for the outer diameter of solid portion 114 because its decayparameter can be readily varied to better transition to the Gaussiandistribution of Equation (1) for hollow portion 112, and the exponentialdecay provides a smooth and gradual yet rapid transition in outerdiameter D_(c) conducive to propagation of ultrasound with minimalerrant reflection and standing waves.

The inverse exponential distribution profile, i.e., Equation (9), ofsolid portion 114 of horn 110 next interfaces at first or proximal end178 of tip lead 120 at a chisel angle θ uniquely selected because itsupports a termination of total length L4 of tip lead 120. Total lengthL4 resulting from selected chisel angle θ is a parameter beneficial toestablishing resonant frequency, and promotes a reasonable transition tothe inverse exponential profile R(x) of Equation (9). Ultrasonic horn100 in one embodiment is formed of titanium 6A14V although othermaterials such as stainless steel can be used. Horn 100 resonates with alength near but not exactly a quarter wavelength λ/4 (or multiplesthereof) of the speed of sound in titanium. In fact, unless transducer150, connecting body 140, and horn 110 resonate, the stroke amplitudeand propagation of ultrasound is minimal. Chisel angle θ is the anglebetween central longitudinal axis A of elongated member 110 and chiselinterface or opposing outside surfaces 118 a and 118 b, and is bestconsidered as a tangent function that is projected back from therequired termination of length of horn 100. Vertical dimension Y(x) oftip lead 120 is therefore a function of chisel angle θ, as given by thefollowing equation:Y(x)=x tan θ  (10)

Vertical dimension Y(x) can also be considered to be the distancebetween the central longitudinal axis A and the respective opposingsurfaces 118 a and 118 b. Chisel angle θ also presents interfacesurfaces 118 a and 118 b to the ultrasound so that forward propagationoccurs rather than errant reflection or mode conversion which couldoccur at greater angles. Chisel angle θ also functions well in chiselingbone, where greater angles can promote burrowing and greater resistance,and lesser angles cause slippage. In one embodiment of the presentdisclosure, θ is about 35°, although other values of θ can be used.

It should be noted that while the vertical dimension of tip lead 120 isgiven by chisel angle θ as described above for Equation (10) as bestillustrated in FIG. 4 and FIG. 6, horizontal dimension of tip lead 120continues to be given by the inverse exponential profile distributionR(x)={D_(c)/2}{e^(−(1/2)x)} given by Equation (9).

FIG. 9 illustrates the horn profile in one embodiment using solid modelviews of the actual profile. The horn profile is shown still somewhatmagnified but the transition of the inverse exponential profile toGaussian and to the chisel angle are visualized closer to the actualshape. It should be noted that although tip lead 120 appears to come toa sharp point in FIGS. 7 and 9, in actuality, tip lead 120 is, in oneembodiment, flat or chisel/awl shaped as best shown in FIG. 1B.

In one embodiment of the present disclosure, FIGS. 10A and 10B throughFIG. 14 illustrate an ultrasonic horn which is designed for a differentresonant frequency such as 36 kHz. More particularly, ultrasonic horn200 is identical to ultrasonic horn 100 of FIGS. 1 through 9 except foran extension member 202 which extends overall length of horn 200. Inview of the similarity between horns 100 and 200, like parts aresimilarly numbered and only those parts which are unique to ultrasonichorn 200 are numbered differently.

As best illustrated in FIGS. 11 and 12, extension member 202 has aproximal end 206 and a distal end 208. An adapter 230 has a proximal end272 and a distal end coinciding with proximal end 206 of extensionmember 202. Adapter 230 includes, extending distally from proximal end272, a fillet 232, a nut 234 and a flange 236 terminating at proximalend 206 of extension member 202. Length L6 is the length of fillet 232and nut 234 from proximal end 272 of adapter 230 to leading edge 238 offlange 236. A flared member 204 is disposed at proximal end 174 ofelongated member 110 and at distal end 208 of extension member 202.Adapter 230 and flared member 204 are, in one embodiment, unitarilyconnected to extension member 202.

It should be noted that the extension member, 202, is shown as astraight circular cylinder or tube. However, in commercially availableembodiments, such as the CUSA EXcel™ 36 kHz Model Curved Extended MicroTip, C4611 (See the 2005 CUSA EXcel™ Ultrasonic Surgical AspiratorProduct Catalog by Tyco Healthcare LP;www.radionics.com/products/cusa/cusa-catalog.pdf), this extension membercan be curved. An embodiment of the ultrasonic horn 200 disclosed hereinhas been tested and can be readily manufactured with a curved extensionmember of about 13° or less. The curved extender affords improvedline-of-sight to the distal end by removing the connecting body andresonator further from the field of view.

Constant diameter channel 160 extends through adapter 230, extensionmember 202 and flared member 204. The outer diameter of extension member202 is substantially constant and is greater than outer diameter D_(gO)of elongated member 110 at proximal end 174. Therefore, flared member204 forms a transition member between the outer diameter of extensionmember 202 and outer diameter D_(gO) of elongated member 110 at proximalend 174. Dimension L1′ is the length along central longitudinal axis Aextending distally from leading edge 238 of adapter 230, extensionmember 202 and flared member 204, to distal end 174 of flared member204.

As a result, length Lg′ of a Gaussian profile portion 284 of ultrasonichorn 200 is defined by sum L_(1′-2) of lengths L1′ and L2, or Lg′32L1′+L2. L5′ is the length of ultrasonic horn 200 extending distally fromleading edge 238 of flange 236 to distal end 180 and is equal to the sumof L1′, L2, L3 and L4. Therefore, L5′ equals length L′_(tip) ofultrasonic horn 200 and L5′=L′_(tip) The approximate total length ofchannel 160 is the sum of L6′, L1′ and L2 or L6′ and Lg′. Tip 290 isdefined as the portion of ultrasonic horn 200 extending distally fromleading edge 238 of flange 236 to distal end 180.

Proximal end 272 of adapter 230 is configured to connect to a connectingportion 240 which is disposed in proximity to proximal end 272 ofadapter 230. A proximal end 242 of connecting portion 240 is configuredto connect to a distal end of a resonator 250. Again, as is the casewith resonator 150, resonator 250 includes, in one embodiment, amagnetostrictive transducer, although other transducer types can beincluded such as a piezoelectric transducer. Resonator 250 is suppliedpower from a generator (not shown) such that resonator 250 operates at adesired resonant frequency, such as in the range of 36,000 Hz (36 kHz).Lengths L1′, L_(1-2′), and L5′ of ultrasonic horn 200 are determined inthe same manner as determined for ultrasonic horn 100, taking intoconsideration in this case connecting body 240 and resonator 250 whichare designed for a resonant frequency of about 36 kHz. As is the case ofultrasonic horn 100, tip lead 120 at distal end 180 is of a flat orchisel/awl shape as best shown in FIG. 10B.

EXAMPLE

In one embodiment of horn 100, as indicated in FIG. 15, a 23 kHzresonant frequency titanium tip lead 120 of the profile discussed wasdeveloped to match the design frequency f_(i) of the existing CUSA™transducer. FIG. 15 illustrates the benefits of being able to transfermodels to automated contouring machine practices, wherein the results ofmodeling of the area function of the Gaussian and associated outsidediameters, D, and internal hole diameters, d, are provided. Inparticular, the following diameters are shown in FIG. 15 and in theassociated table of data: (a) D_(gO) is the outer diameter of elongatedmember 110 along hollow portion 112, which varies as a function of x, ininches; (b) d_(g) is inner diameter of hollow portion 112 of elongatedmember 110 and is substantially constant.

A particular benefit of the mathematical approach to the profile, whichincludes the wall defined by the Gaussian and channel, the decayingexponential solid, and tangent function of the chisel was that theresonant frequency f_(i) predicted was achieved in the first actualdevices. Solid modeling and finite element analysis (FEA) bettercaptured ancillary geometry, such as flanges, cylinders to be threaded,and side drilled holes, that were too complex to be mathematicallymodeled. The modal analysis of the solid models generally predicted aresonant mode with a repeatable shift in frequency, i.e., the predictedresonant frequency was about 4% greater than measured on actual devices.The solid modeling and FEA greatly facilitated evaluation of stresses,node locations, and prediction of amplitude of the stroke of the horn.The majority of the horn profile was also readily accomplished incontour turning operations, with only chisel/awl tip 180 of horn 100requiring additional machining.

The first row of data (1) indicated a predicted frequency f_(i) of23,065 Hz for the new horn 100. As an illustration, a second row of data(2) revealed that even a 0.001 inch deviation in one profile diameter,i.e., D_(c) from 0.120 to 0.121 in., shifts the horn from designresonance f_(i) by about 150 Hz, i.e., f_(i) shifts from 23,065 Hz to22,908 Hz, where stroke amplitude and propagation of ultrasound areminimal, resulting in an adverse condition shifting the horncharacteristics out of resonance conditions. The third row of data (3)in FIG. 15 shows results of the first five horns characterized that werefabricated to the model, and these were remarkably on the resonantfrequency target f_(i) without a Gaussian profile adjustment. The datain the third row (3) were acquired with a power meter at a 40% amplitudesetting of the CUSA™. Stroke amplitude was measured optically. The hornsaddressed herein have symmetric stroke, where the distal end vibratespositively and negatively from its neutral or datum position. Strokeamplitude is defined as the peak excursion of the distal end of thehorn. Horn displacement is generally defined as the peak-to-peakamplitude, and for symmetric motion, the horn displacement is twice thestroke amplitude. As can be seen, the manufacturing practice affordedwith the profile has the required precision for production.

FIG. 16 is a table of experimental data comparing parameters of anultrasonic horn according to the present disclosure to parameters of anultrasonic horn of the prior art. More particularly, blocks 1 a and 1 bindicate parameters and data pertaining to an ultrasonic horn of theprior art with a standard tip, in particular, the CUSA EXcel™ 23 kHzModel C4601S (See the 2005 CUSA EXcel™ Ultrasonic Surgical AspiratorProduct Catalog by Tyco Healthcare LP;www.radionics.com/products/cusa/cusa-catalog.pdf). Blocks 2 a and 2 bindicate parameters and data which pertain to an ultrasonic horn of thepresent disclosure such as ultrasonic horn 100 having a nominal resonantfrequency of 23 kHz as previously described with respect to FIGS. 1A, 1Bthrough FIG. 9.

It should be noted that the value of D_(c) in row 1 a is only 0.09888in. versus D_(c) of 0.120 in. in row 1 of FIG. 15. With respect to thehorn configuration corresponding to the data of FIG. 15, the diameterD_(c) was increased to achieve a larger wall thickness for the Bone Tip,such that it would have greater structural rigidity to lateral loadsthat could result from pushing on the chisel. The minimum wall thicknesswas increased from about 0.010 in to greater than about 0.020 in.

The specific parameters indicated in FIG. 16 are defined as follows:

E_(g) is the Elastic Modulus (sometimes called Young's Modulus) of thetitanium material used to fabricate the horns;

w/v is the weight density or weight per unit volume;

ρ is the density in IPS (Inch Pound System) or ρ=(w/V)(1/g), adopting agravitational acceleration of 9.8 m/s² at sea level;

L_(tip) is the length of the Gaussian, L_(g), plus the length of theremainder of the horn, L_(c);

C_(g) is the acoustic velocity of the titanium metal;

D_(go) is the large diameter of the Gaussian portion;

d_(g) is the channel internal diameter;

D_(c) is the small diameter of the Gaussian portion;

d_(c) is the channel internal diameter, and is equal to d_(g) in thecase of a constant diameter hole;

S_(go) is the cross-sectional area of the wall of the Gaussian largediameter minus the cross-sectional area of the channel;

S_(c) is the cross-sectional area of the wall of the Gaussian smalldiameter minus the cross-sectional area of the channel;

N is the Gaussian ratio of S_(go)/S_(c);

ω_(i) is the designed angular frequency in radians/second of theGaussian portion;

f_(i) is the frequency in Hz, or ω_(i)/2π;

L_(g) is the length of the Gaussian portion or the distance from thelarge diameter of the Gaussian portion to the end of the Gaussianportion at its small diameter end. For all of the ultrasonic horns ofthe present disclosure, this length corresponds to the distance from theleading edge, such as leading edge 138 of the flange 136, to the end ofthe Gaussian portion at its small diameter end; and

L_(c) is the distance from the end of the Gaussian to distal end of thehorn.

The data designated as block 2 a correspond to the First Pass Gaussianfor Solid Distal End data.

The data designated as block 2 b are of particular interest as theydetermine the characteristics for the New Profile. The first column,index, is an index to generate evenly spaced x values. The next column,xg, is the x distance from a datum of zero at the first large diameterof the Gaussian, which corresponds to leading edge 138 of flange 136 onadapter 130 that mates with connecting body 140. This is describedearlier in the remarks. The profile area is calculated for plottingpurposes in the next column, and each successive value is smaller fromthe large diameter of the Gaussian to the small diameter of theGaussian. The D_(g)(x) column is the calculated diameter at each xlocation, and the positive and negative values of the radii arecalculated in the next columns, primarily for plotting purposes. The NewProfile xg, distances end at index 20 with a distance of 1.8802 inch.The exponential begins using the xtip index at 1.8802. There is onepoint of overlap in the plots. The Diameter DcNew1e^((−0.5x)) is thenext column, which starts calculation of the adjacent exponential decaydiameter. The positive and negative radii are calculated in the nextcolumns for plotting purposes. The positive and negative tangent valuesare calculated for the chisel end 180 of the tip lead 120 in thesubsequent columns. The spreadsheet enables viewing the continuity andblend of the profiles in very simple plots. The approach has evolvedwhere the blends are now determined automatically on the spreadsheet.

It is of interest to note that the frequency of the actual devicesoperated at 40% amplitude was 23,050 Hz, but operating the ultrasonichorn assemblies of the present disclosure at 100% amplitude results in areduction in frequency, where stable operation approaches the 23,000 Hz.The ultrasonic horn assemblies of the present disclosure reach a thermalequilibrium within two minutes. The higher amplitude quiescent point andresulting increased temperature reduces frequency. Measurements aretaken at both 40% and 100% amplitude, but because the voltage waveformsbecome distorted at 100% amplitude, due to limitations of the powersupply, comparative data on the horns are best viewed at a loweramplitude of operation.

FIG. 17 illustrates ultrasonic horn 100 having a nominal resonantfrequency of 23 kHz in an ultrasonic horn assembly 1700 whichincorporates connecting body 140 and ultrasonic resonator 150. Resonator150 has a core stack 1750. Based on the data of blocks 2 a and 2 b ofFIG. 16, ultrasonic horn assembly 1700 has a node 1702 at about thecenter of core-stack 1750 of resonator 150, where displacement is zero.Core-stack 1750 has somewhat symmetric antinodes 1704 and 1706 near aproximal end 1712 and distal end 1714, where displacement is aboutmaximum. Given node 1702 at the center of core-stack 1750, next nodewould be expected with about a λ/2, spacing. It should be noted that theacoustic velocities of the constituent elements of core stack 1750 andconnecting body 140 are different, and the geometry of connecting body140 is quite complex. Next node 1708 occurs nearer to the interfacebetween connecting body 140 and proximal end 172 of ultrasonic hornadapter 130. Next antinode 1710 is located in the vicinity of distal end180 of tip 190 of ultrasonic horn 100, such that all the strain in thehorn is utilized in maximizing horn displacement.

It should be noted that the definition of nodes, their locations, andtypes are not as simple as often exclaimed or shown in the prior art.One of the issues complicating the definition and location of nodes andantinodes is that more than one mode (resonant frequency) exists for anultrasonic horn assembly such as ultrasonic horn assembly 1750. The 23kHz ultrasonic horn assembly for example has four substantial modes overthe range of 10,000 Hz to 50,000 Hz. The generator creates a conditionwhere the 23 kHz mode is dominant by employing a self-sustainingbandwidth limited oscillator. Without an active filter in the amplifier,the ultrasonic horn assembly could resonate at the incorrect frequency.The additional modes are overtones or undertones, and not harmonics.Even with a simple geometry, the modes are not integral multiples offrequency and the nodes are not located at exact fractional wavelengths.Each mode may contribute one or more nodes and antinodes depending onthe frequency and geometry. A further complication is that the nodes mayhave different characteristics. For example, some nodes may have adisplacement of zero but first and second derivatives of zero or otherthan zero. The geometry is very complex, and not simply a rod or bar,exponential, or Gaussian, which can be exactly representedmathematically. The acoustic velocities of the constituent materials ofthe core-stack 1750, connecting body 140, and tip 190 are different, andit may be intuitive that this may impact simple fractional wavelengthspacing. The determination of allowable resonant frequencies and nodelocations is not simple, but if one can write equations for each of theconstituent elements, and solve the roots of the overall equation(mathematically or graphically), the modes and approximate location ofnodes can be determined, within the extent of the accuracy of thegeometrical representation. Alternatively, the previously mentionedPRO/Mechanica or a similar FEA package can be used to perform modalanalysis, and the relative nodes of zero displacement can be monitoredin simulations. It is this simulation that is exhibited in FIG. 17.

In one embodiment of the present disclosure, FIGS. 18-20 illustrate anultrasonic horn 300 having a tip lead 320 of elongated member 310 at adistal end 380. Ultrasonic horn 300 is otherwise identical to ultrasonichorns 100 and 200 previously described except that tip lead 320 includesa first surface 324 which is substantially flat or planar while a secondor opposing surface 318 substantially follows the contour of solidportion 114 of elongated member 310 whose radius R is formed accordingto an inverse exponential profile distribution.

More particularly, dimension L3 is the length of solid portion 114 ofelongated member 310 whose radius R is formed according to an inverseexponential profile distribution. Length L3 of solid portion 114 ofelongated member 310 extends from approximately second or distal end 176of channel or central hole 160 to first or proximal end 178 of elongatedmember 310 at tip lead 320. Dimension L4″ corresponds to the length ofchisel and awl tip lead 320 and is the length of a solid portion 316 ofelongated member 310 extending from first end 178 of elongated member310 at tip lead 320 to second end 380 of elongated member 310. Elongatedmember 310 is thereby a completely solid mass from intermediate point176 to second end 380. Therefore, tip lead 320 extends from first orproximal end 178 to second or distal end 380 of elongated member 310.Radius R″, or more correctly, height Y″, of tip lead 320 forms surface324 according to a unilateral tangential or linear profile distributionsuch that Y″=x tan θ″. That is, height Y″ is proportional to the tangentof angle θ. L5″ is the total length of ultrasonic horn 100 extendingfrom first or proximal end 172 of adapter 130 to second or distal end380 of elongated member 310 and is equal to the sum of L1, L2, L3 andL4″. When ultrasonic horn 300 is connected to connecting portion 140,channel 160 extends through connecting portion 140 and ends before theresonator 150. Tip 390 is defined as the portion of ultrasonic horn 300extending distally from leading edge 138 of flange 136 to distal end180.

As best shown in FIG. 18, substantially flat surface 324 is formed at anangle α with respect to the centerline A-A to enable a plunge cutdirection A′. The plunge cut angle α enables a line-of-sight C′ by theuser directly to the targeted object. In addition, the substantiallyflat surface 324 is formed at a rake angle β with respect to lateralaxis Z. Rake angle β provides clearance to access underlying tissue.Substantially flat surface 324 is formed of an abrasive mill-filestructure so that surface 324 supports lateral abrasion, as indicated byarrow B′.

Distal end 380 of tip lead 320 has a semi-circular planar surfaceconfiguration 322, such that distal end 380 of ultrasonic horn 300 is inthe form of a chisel and an awl. As discussed previously, tip 380 ofultrasonic horn 300 is blunt or dull. The existing blunt edge is about0.0125 mm (0.005 inches) wide. The boring of holes with ultrasonic horn300 is better facilitated with slightly semi-circular manual motion;however plunge cuts in bone and wood have been accomplished with justlongitudinal motion. As discussed before with respect to ultrasonichorns 100 and 200, the combination of the chisel and awl distal end 380of horn 300 supports defined cutting or abrasion of sections, planes,notches, grooves, and holes in bone. In particular, chisel and awldistal end 380 of ultrasonic horn 300 in combination with the abrasivemill-file structure of surface 324 is particularly useful for orthopedicsurgery and neurosurgery.

In one embodiment of the present disclosure, FIG. 21 illustrates anultrasonic horn 400 having a tip lead 420 of elongated member 410 at asecond or distal end 480. Ultrasonic horn 400 is otherwise identical toultrasonic horns 100, 200 and 300 previously described. Moreparticularly, elongated member 410 extends from a first or proximal end474 and includes a first hollow portion 412 extending distally to afirst intermediate point 476 distal to a user between which first hollowportion 412 of elongated member 410 has a Gaussian profile. From firstintermediate point 476, elongated member 410 includes a second hollowportion 414 extending distally to a second intermediate point 482 distalof first intermediate point 476 between which second hollow portion 414of elongated member 410 has a straight or constant diameter profile.Constant diameter profile corresponds to small diameter d_(c) of theGaussian profile at first intermediate point 476. From secondintermediate point 482, elongated member 410 includes a third hollowportion 426 extending distally to a third intermediate point 478 distalof second intermediate point 482 between which third hollow portion 426of elongated member 410 has a flared exponential profile. From thirdintermediate point 478, elongated member 410 includes a fourth hollowportion 428 extending distally to a generally planar distal end 480 ofelongated member 410 between which fourth hollow portion 428 ofelongated member 410 has an inverse conical profile. Fourth hollowportion 428 having an inverse conical profile forms a tip of elongatedmember 410, with tip 428 extending from third intermediate point 478 todistal end 480 of elongated member 410. Tip 428 includes an abradedouter surface 418 formed according to the inverse conical profile. Asubstantially constant diameter channel 460 is formed within elongatedmember 410 by the hollow portions. Channel 460 extends from proximal end474 through first hollow portion 412 having a Gaussian profile, throughsecond hollow portion 414 having a straight or constant diameter profileof the small diameter of Gaussian portion 412, through third hollowportion 426 having a flared exponential profile, and through fourthhollow portion or tip 428 to distal end 480. Channel 460 has an aperture490 at distal end 480.

Although not shown specifically in FIG. 21, ultrasonic horn 410 is alsoconfigured with an adapter such as adapter 130 in FIGS. 1A and 2-6, andmay similarly be connected to a connecting body 140 and a resonator 150,as shown therein. When ultrasonic horn 400 is connected to connectingportion 140, channel 460 extends through connecting portion 140 endingbefore resonator 150.

Conical surface 418 is formed at an offset angle δ with respect tocenterline A-A to enable a line-of-sight C′ by the user directly to thetargeted object. In addition, inverse conical surface 418 is formed ofan abrasive mill-file structure so that surface 418 supports lateralabrasion, as indicated by arrow B′. It should be noted that themill-file structure can be machined over the full 360° of the distalend, or limited to suit particular surgical requirements, e.g., in oneembodiment, the abrasive structure is machined over less than 120°.

Therefore, as compared to ultrasonic horns 100, 200 and 300, ultrasonichorn 400 differs in that channel 460 extends entirely through elongatedmember 410, whereas channel 160 extends only to intermediate point 176(See FIGS. 3-6) where a transition occurs between the Gaussian profileof hollow portion 112 and the inverse exponential profile of solidportion 114. In addition, elongated member 410 includes a straight orconstant diameter section portion 414, flared exponential portion 426and inverse conical portion 428 as compared to opposing surfaces 118 aand 118 b of tip lead 120. In one embodiment, the major diameter of theinverse conical fourth portion 428 at the third intermediate point 478is less than about 3 mm and inverse conical surface 418 is formed at anoffset angle δ of about 10°. Other diameters and offset angles may beused. Through the modeling, simulation, and initial manufacturing phase,the major diameter of less than 3 mm and offset angle δ of less than 10°has been maintained. The offset angle δ may be increased to providealternative line of sight options for other procedures. An opening 492in a patient's body through which ultrasonic horn 400 is used generallyhas to be larger for greater offset angles. FIG. 22 illustratesultrasonic horn 400 of FIG. 21 further including extension member 202and having a nominal resonant frequency of 36 kHz in an ultrasonic hornassembly 2200 and which incorporates connecting body 240 and ultrasonicresonator 250. As previously described herein, the extension member 202can be a straight circular cylinder or tube or be curved to 13° or less.

FIG. 22 further illustrates node and antinode locations resulting froman experimental analysis analogous to that which resulted in theexperimental data of FIG. 16. More particularly, resonator 250 enclosesa core stack 2250. Resonator 250 has a proximal end 2222 and a distalend 2224. Ultrasonic horn assembly 2200 has a node 2202 just distal ofthe center of core-stack 2250 of resonator 250, where displacement iszero. Node 2202 is not exactly on center because it is influenced bymore than the simple geometry of core-stack 2250. Core-stack 2250contributes to an antinode 2204 within proximal end 242 of connectingbody 240, where displacement is about maximum. Next node 2204 is atflange 236 of adapter 230 and just beyond threads of leading edge 238 offlange 236 mating adapter 230 to connecting body 240. Again, it shouldbe noted that the acoustic velocities of the constituent elements aredifferent, and the geometry of connecting body 240 is quite complex.Next node 2208 occurs proximal of and in the vicinity of distal end 208of extension member 202. Distal end 208 coincides with the proximal endof flared transition member 204. An antinode 2210 occurs at proximal end2222 of ultrasonic resonator 250. Another antinode 2212 occurs inextension member 202 about midway between nodes 2206 and 2208. At thestraight or constant diameter portion 414 in proximity to distal end 480of ultrasonic horn 400 is yet another antinode 2214, such that all thestrain in horn assembly 2200 is utilized in maximizing horndisplacement.

In one embodiment, FIG. 21 illustrates pre-aspiration apertures or holes494 formed through the walls on opposing sides of straight or constantdiameter second portion 414. Pre-aspiration apertures 494 of elongatedtip portion 410 may be employed in conjunction with channel 460, which,as previously noted, extends from proximal end 474 through first hollowportion 412 having a Gaussian profile, through second hollow portion 414having a straight or constant diameter profile of the small diameter ofGaussian portion 412, through third hollow portion 426 having a flaredexponential profile, and through fourth hollow portion or tip 428 todistal end 480. An example is the CUSA EXcel™ 36 kHz Model CurvedExtended Micro Tip, C4611 (See the 2005 CUSA EXcel™ Ultrasonic SurgicalAspirator Product Catalog by Tyco Healthcare LP;www.radionics.com/products/cusa/cusa-catalog.pdf). The pre-aspirationholes 494 can be optionally used to suction a portion of the irrigationliquid employed through the channel to aid in cooling the tip. Thepre-aspiration holes 494 can also reduce misting caused by cavitation atthe distal end of tip, thereby improving viewing via endoscopes ormicroscopes.

In terms of applications, ultrasonic horn 400 and ultrasonic hornassembly 2200 are particularly useful for cranial-based surgery, whereopening 492 is larger than when performing transsphenoidal orendoscopic-nasal approaches.

In one embodiment of the present disclosure, FIG. 23 illustrates anultrasonic horn 500 having a tip 520 of elongated member 510 at a secondor distal end 580. Ultrasonic horn 500 is otherwise identical toultrasonic horn 400 previously described. More particularly, elongatedmember 510 extends from a first or proximal end 574 and includes a firsthollow portion 512 extending distally to a first intermediate point 576distal to a user between which first hollow portion 512 of elongatedmember 510 has a Gaussian profile. From first intermediate point 576,elongated member 510 includes a second hollow portion 514 extendingdistally to a second intermediate point 582 distal of first intermediatepoint 576 between which second hollow portion 514 of elongated member510 has a straight profile of the small diameter of the Gaussian. Fromsecond intermediate point 582, elongated member 510 includes a thirdhollow portion 526 extending distally to a third intermediate point 578distal of second intermediate point 582 between which third hollowportion 526 of elongated member 510 has a flared exponential profile.From third intermediate point 578, elongated member 510 includes afourth hollow portion 528 extending distally to a generally planarsecond or distal end 580 of elongated member 510 between which fourthhollow portion 528 has a conical profile. Fourth hollow portion 528having a conical profile forms a tip of elongated member 510, with tip528 extending from third intermediate point 578 to distal end 580 ofelongated member 510. Tip 528 includes an abraded outer surface 518formed according to the conical profile. A substantially constantdiameter channel 560 is uniformly formed within elongated member 510 bythe four hollow portions 512, 514, 526 and 528. Channel 560 extends fromproximal end 574 through hollow portion 512 having a Gaussian profile,through the hollow portion 514 having a straight or constant diameterprofile of the small diameter of Gaussian portion 512, through hollowportion 526 having a flared exponential profile, and through tip 528 todistal end 580. Channel 560 has an aperture 590 at distal end 580.

Although not shown specifically in FIG. 23, ultrasonic horn 510 is alsoconfigured with an adapter such as adapter 130 in FIGS. 1A and 2-6, andmay similarly be connected to a connecting body 140 and a resonator 150,as shown therein. When ultrasonic horn 500 is connected to connectingportion 140, channel 560 extends through connecting portion 140 and endsbefore resonator 150.

Conical surface 518 is formed at an angle γ with respect to centerlineA-A to enable a line-of-sight C′ by the user directly to the targetedobject. In addition, conical surface 518 is formed of an abrasivemill-file structure so that surface 518 supports lateral abrasion, asindicated by arrow B′. When the abrasive surface 518 is brought normalto the bone, the proximal end 574 rotates out of the line of sight.

Therefore, as compared to ultrasonic horns 100, 200 and 300, ultrasonichorn 500 also differs in that channel 560 extends entirely throughelongated member 510, whereas channel 160 extends only to intermediatepoint 176 (See FIGS. 3-6) where a transition occurs between the Gaussianprofile of hollow portion 112 and the inverse exponential profile ofsolid portion 114. In addition, elongated member 510 includes a straightsection 514, having a straight or constant diameter profile. Constantdiameter profile corresponds to small diameter d_(c) of the Gaussianprofile at first intermediate point 576. Elongated member 510 alsoincludes flared exponential portion 526 and conical portion 530 ascompared to opposing surfaces 118 a and 118 b of tip lead 120.

In one embodiment, the major diameter of conical fourth portion 528 atthird intermediate point 578 is less than about 4 mm-and conical surface518 is formed at an offset angle Aγ of about 10°. Other diameters andoffset angles may be used. It is envisioned that the offset angle γ mayinclude values as large as 45°. In terms of applications, ultrasonichorn 500 is particularly useful for transsphenoidal or endoscopic-nasalapproaches. In comparing an opening 592 required for access with thelateral abrasion surface normal to a bone for horn 500 embodied in FIG.23 to required opening 492 for horn 400 in FIG. 21, it is clear that theinnovation of horn 400 in FIG. 21 enables passage and operation througha small opening, such as employed in approaching tumors for removalthrough the nose. In particular, an endoscope employed in the samenostril or inserted into a second nostril, and located just in back ofthe flared exponential, would provide the line-of-sight necessary.Additionally, these transsphenoidal and endoscopic nasal approachesoften require further opening of bony cavities, such as in the sphenoidsinus. It has been observed that when the openings are extended with amanual tool such as a Kerrison or manual cutting device, the bonefractures in an unpredictable way, often leading to excessive bleeding.The horn in FIG. 23, would readily facilitate operation via a passage ofless than about 4 mm, support line-of-sight viewing of the area underoperation with an adjacent endoscope, and provide controlled abrasionfor marginally opening bony cavities.

In one embodiment, FIG. 23 illustrates pre-aspiration apertures or holes594 formed through the walls on opposing sides of straight or constantdiameter second portion 514. Pre-aspiration apertures 594 of elongatedtip portion 510 may be employed in conjunction with channel 560, which,as previously noted, extends from proximal end 574 through first hollowportion 512 having a Gaussian profile, through second hollow portion 514having a straight or constant diameter profile of the small diameter ofGaussian portion 512, through third hollow portion 526 having a flaredexponential profile, and through fourth hollow portion or tip 528 todistal end 580. Again, an example is the CUSA EXcel™ 36 kHz Model CurvedExtended Micro Tip, C4611 (See the 2005 CUSA EXcel™ Ultrasonic SurgicalAspirator Product Catalog by Tyco Healthcare LP;www.radionics.com/products/cusa/cusa-catalog.pdf). The pre-aspirationholes 594 can be optionally used to suction a portion of the irrigationliquid employed through the channel to aid in cooling the tip. Thepre-aspiration holes 594 can also reduce misting caused by cavitation atthe distal end of tip, thereby improving viewing via endoscopes ormicroscopes.

The 23 kHz devices manufactured readily removed bone at even low (40%)amplitude settings of the CUSA™ with little physical force by thesurgeon, better relying on the fragmentation of the material withconcentrated ultrasound and resultant mechanical forces. With the newhorn, cutting and abrasion of bone was effective going with or acrossthe apparent grain of bone, and on edge of sectioned bone. Irrigationliquid (e.g. saline) is continuously provided via a polymer fluesurrounding the horn, as is done with the ultrasonic aspiration horns.With optional settings of the CUSA™, the concentrated ultrasound is alsoobserved to promote cavitation in the liquid at the relatively blunt ordull surface of the cutting end of the chisel, thereby better supportingmaterial removal without a sharpened end like a wood plane or scalpel. Asharpened end could chip, and also be a hazard to tissue even when notultrasonically excited, such as in transiting a nasal cavity. Along withamplitude control, the selectivity feature of the commercially availableCUSA™, which limits reserve power, can be utilized to remove very finelayers of bone with the chisel, more like monolayers or planes. Thelow-quiescent power of the new horn afforded by the profile is as low asthe commercially available ultrasonic aspiration horns that do not havesolid distal ends. The low quiescent power of the new horn, as shown ininitial data to be less than 20 Watts, affords adjustment of reservepower from a few Watts to as great as 80 Watts. Bulk removal of bone isreadily accomplished with well defined cutting or abrasion of sections,planes, notches, grooves, and holes in bone. A wide range of cutting orabrasion capability is available based on settings of amplitude andreserve power.

The device described is just one embodiment of the use of the inverseexponential profile with the Gaussian and solid distal end geometry. Ofcourse, straight extenders of multiple quarter wavelengths between thethreaded end and Gaussian are often employed to make the horns longer,and these can be readily employed with the new horn, as discussedpreviously with respect to the embodiment of the present disclosure ofultrasound horn 200 and the corresponding FIGS. 10A, 10B through 14.Therefore, if extension 202 is of a length such as λ/2, the resonantfrequency of ultrasonic assembly of resonator 250, connecting body 240and ultrasonic horn 200 is not substantially changed or affected by thepresence of extension 202. Again, it should be noted that the extensionmember, 202, is shown as a straight circular cylinder or tube. However,in commercially available embodiments, such as the CUSA EXcel™ 36 kHzModel Curved Extended Micro Tip, C4611 (See the 2005 CUSA EXcel™Ultrasonic Surgical Aspirator Product Catalog by Tyco Healthcare LP;www.radionics.com/products/cusa/cusa-catalog.pdf), this extension member202 can be curved. An embodiment of the ultrasonic horn 500 disclosedherein can be readily manufactured with curved extension members ofabout 13° or less. The curved extender affords improve line-of-sight tothe distal end by removing the connecting body and resonator furtherfrom the field of view. It should also be noted that the horn design isnot unique to magnetostrictive transducers; therefore, piezoelectricdevices could be used. It should be apparent that alternative soliddistal end geometries, such as more blunt ends with abrasive surfaces orflared horns, etc, could be similarly constructed.

It can be seen therefore that the embodiments of the present disclosureprovide an Ampulla (Gaussian) to inverse exponential to chisel/awldistal end profile which affords mechanical gain and propagation ofultrasound with minimal errant reflection and standing waves that couldlimit transmitted sound and reduce horn stroke amplitude. Quiescentpower is similar to ultrasonic aspiration horns that do not have soliddistal ends, and reserve power is far greater than is needed to readilycut or abrade bone. Along with amplitude control and the selectivityfeature of the commercially available CUSA™, which limits reserve power,the ultrasonic horn of the present disclosure can be utilized to removevery fine layers of bone with the chisel, in monolayers or planes.

The ultrasonic horn with the combined chisel and awl distal end of thepresent disclosure used in conjunction with the CUSA™ control system,provides the fine control typically exhibited by ultrasonic abrasivedevices with file-like structures, while better supporting definedcutting or abrasion of sections, planes, notches, grooves, and holes inbone. Furthermore, the new horn profile affords superior bulk removal ofbone, whereas bulk removal of bone is a limitation of existingultrasonic devices.

As compared to ultrasonic surgical instruments with file-like abrasivestructures, the new horn is blunt or dull on its very end and morecone-like with a monotonically increasing diameter, thereby improvingsafety in insertion, and requiring minimal space. In addition, ascompared to such surgical instruments, the new horn can be optionallyoperated such that the concentrated ultrasound afforded with thechisel/awl distal end results in cavitation, the latter aiding incutting and abrading bone. The high mechanical forces known to accompanycavitation afford work beyond simple friction and abrasion via file-likestructures.

As previously discussed, the inverse exponential profile of the presentdisclosure with the decay parameter selected to uniquely match theGaussian profile provides an improved horn for propagation of highamplitude ultrasound, as previously discussed. The profile of the newhorn beyond the Gaussian is greatly simplified as compared to ultrasonichorns having a tip with a multifaceted profile. The majority of theprofile of the new horn can be manufactured employing automatic contourturning operations, as previously discussed. The chisel angle of the newhorn is more conducive to forward propagation of ultrasound being 35°,versus 45° for horns having a multifaceted tip. As a result, theultrasonic horn of the present disclosure is capable of beingmanufactured with a simple turning operation, which is not the case withhorns having a tip with a multifaceted profile.

In view of existing manually spring-activated surgical instruments usedin opening or extending bony cavities such as the sinus bone cavity toaccess tumors in the brain, e.g., a manual device with a sharp orserrated edge that crimps bone or tenacious tissue when hand actuated,such as a Kerrison™ bone punch, the ultrasonic horn with the chisel/awldistal end of the present disclosure affords improved control. With suchmechanical spring-activated instruments, bone is crimped, cut, andremoved. It has been observed that unpredictable fracturing may occurwith crimping, which can result in severe bleeding. An alternative tothe Kerrison™ bone punch is specifically sought for delicately extendingthe openings in bony cavities. It is envisioned that the controlledextension afforded with cutting and abrasion with the new horn overcomesthese potential problems

Furthermore, it has been observed that existing motorized high speed(e.g. 40,000 to 60,000 RPM) drills with diamond impregnated or flutedball cutting ends presently used in surgical approaches may create somehazards including winding of tissue in proximity to the drill shaft androtating ball end, whipping of critical anatomy with partially wound-uptissue, and “walking” of the ball in an uncontrolled fashion onirregular and sometimes cylindrical or wedge shaped bone surfaces.Although not all the bone removal tasks performed with these motorizeddrills can be envisioned for the new horn, bulk removal of bone isreadily accomplished with well defined cutting or abrasion of sections,planes, notches, grooves, and holes in bone, and this capability wouldbe better suited in some surgical sites near critical anatomy.

The ultrasonic horns of the present disclosure can be combined withirrigation and aspiration systems such as is disclosed in, for example,FIG. 3 of U.S. Pat. No. 6,214,017 B1 to Stoddard et al., which as notedis incorporated by reference herein in its entirety. Irrigation in theflue aids in cooling the material of the horn which is in flexure.Pre-aspiration holes may be added. The cooling capability can beenhanced by suctioning some portion of the irrigation liquid through theinternal hole of the horn via pre-aspiration.

While the above description contains many specifics, these specificsshould not be construed as limitations on the scope of the presentdisclosure, but merely as exemplifications of preferred embodimentsthereof. Those skilled in the art will envision many other possiblevariations that are within the scope and spirit of the presentdisclosure.

1. An ultrasonic horn configured for use with a surgical ultrasonichandpiece having a resonator that generates ultrasonic waves, theultrasonic horn comprising: a tapered elongated member having a proximalend, a distal end, an intermediate point located between the proximaland distal ends, and a central longitudinal axis, the elongated membertapering from a larger diameter at the proximal end to a smallerdiameter at the distal end; a tip lead configured on the distal end ofthe elongated member, the tip lead being adapted for cutting hard tissueand having a chisel and awl shaped distal end having a chisel angle thatis bisected by the central longitudinal axis of the elongated member,and further having blunt edges, a first planar surface on which thechisel angle is formed, an opposing second surface; and an internalchannel longitudinally disposed within the elongated member, theinternal channel having a substantially constant diameter central holesurrounded by the tapered elongated member along the entire length ofthe internal channel with the internal channel having a closed endlocated at approximately the intermediate point of the elongated memberand extending to the proximal end of the elongated member at whichposition the channel has an open end, whereby the tapered elongatedmember has a hollow portion for the length of the internal channel andprovides the wall for the hollow portion, wherein due to the channelhaving a constant diameter but the elongated member having a taperedouter shape, the thickness of the wall of the elongated membersurrounding the internal channel varies from a larger thickness at theproximal end of the elongated member to a thinner wall thickness at thechannel closed end; wherein the tapered elongated member furthercomprises a solid portion extending from the closed end of the internalchannel to the distal end of the elongated member, the solid portioncomprising a solid mass.
 2. The ultrasonic horn of claim 1, wherein thefirst planar surface has an abrasive mill-file configuration.
 3. Theultrasonic horn of claim 1, further comprising an adapter disposed onthe proximal end of the tapered elongated member, wherein the adapterincludes: a proximal end configured to connect with an ultrasonicresonator; a distal end; a shaft extending outwardly from the proximalend of the adapter in a proximal direction; a connecting member disposedbetween the proximal end and the distal end; and a flange having aleading edge disposed on the distal end of the adapter.
 4. Theultrasonic horn of claim 3, further including a connecting portion, theconnecting portion being configured to couple with a resonator.
 5. Theultrasonic horn of claim 3, wherein the adapter is configured such thatwhen connected with a resonator, the proximal end of the adapter will bedisposed near a node of an ultrasound wave produced by the resonator,and the tip lead of the tapered elongated member will be disposed nearan antinode of an ultrasound wave produced by the resonator.
 6. Theultrasonic horn of claim 3, further including an extension member and aflared member that are disposed between the adapter and the elongatedmember, the extension member and the flared member including anextension of the internal channel of the elongated member and configuredto interconnect with the elongated member such that the extension of theinternal channel is aligned with the internal channel of the elongatedmember, the length of the extension member selected such that theultrasonic horn is configured to operate at a target frequency of about36 kHz.
 7. The ultrasonic horn of claim 1, wherein the ultrasonic hornis configured to operate at a target frequency of about 23 kHz.
 8. Theultrasonic horn of claim 1, wherein the ultrasonic horn is configured tooperate at a target frequency of about 36 kHz.
 9. The ultrasonic horn ofclaim 1, wherein the ultrasonic horn is made of a metal selected fromthe group consisting of stainless steel and titanium.
 10. The ultrasonichorn of claim 1, wherein the first planar surface has a curvilinearedge.
 11. The ultrasonic horn of claim 1, wherein the solid portion ofthe elongated member has an inverse exponential profile and the proximalhollow portion of the elongated member has a Gaussian profile.
 12. Anultrasonic horn configured for use with a surgical ultrasonic handpiecehaving a resonator, the ultrasonic horn comprising: a tapered elongatedmember having a proximal end, a distal end, an intermediate pointbetween the proximal and distal ends, and a central longitudinal axis,the elongated member tapering from a larger diameter at the proximal endto a smaller diameter at the distal end; an adapter disposed on theproximal end of the tapered elongated member; an internal enclosedchannel longitudinally disposed within the elongated member, theinternal enclosed channel having a substantially constant diametercentral hole surrounded by the tapered elongated member along the entirelength of the internal channel with the internal channel having a closedend located at approximately the intermediate point of the elongatedmember and extending to the proximal end of the elongated member atwhich position the channel has an open end, whereby the taperedelongated member has a hollow portion for the length of the internalchannel and provides the wall for the hollow portion, wherein due to thechannel having a constant diameter but the elongated member having atapered outer shape, the thickness of the wall of the elongated membersurrounding the internal channel varies from a larger thickness at theproximal end of the elongated member to a thinner wall thickness at thechannel closed end and the internal channel further extending throughthe adapter; wherein the tapered elongated member further comprises asolid portion extending from the closed end of the internal channel tothe distal end of the elongated member which comprises a solid mass; anda tip lead configured on the distal end of the elongated member, the tiplead having a chisel and awl shape, the tip lead being adapted forcutting hard tissue and having blunt edges, a first planar surface onwhich the chisel shape is formed also having an abrasive mill-fileconfiguration, and an opposing second surface that follows the contourof a solid portion of the elongated member extending distally from theinternal channel.
 13. The ultrasonic horn of claim 12, wherein theadapter includes: a proximal end configured to connect with anultrasonic resonator; a distal end; a shaft extending outwardly from theproximal end of the adapter in a proximal direction; a connecting memberdisposed between the proximal end and the distal end; and a flangehaving a leading edge disposed on the distal end of the adapter.
 14. Theultrasonic horn of claim 12, further including a connecting portion, theconnecting portion being configured to couple with a resonator.
 15. Theultrasonic horn of claim 12, wherein the first planar surface has acurvilinear edge.
 16. The ultrasonic horn of claim 12, wherein the solidportion of the elongated member has an inverse exponential profile andthe proximal hollow portion of the elongated member has a Gaussianprofile.
 17. An ultrasonic horn configured for use with a surgicalultrasonic handpiece having a resonator that generates ultrasonic waves,comprising: a tapered elongated member having a proximal end, a distalend, an intermediate point between the proximal and distal ends, and acentral longitudinal axis, the elongated member tapering from a largerdiameter at the proximal end to a smaller diameter at the distal end; aninternal enclosed channel longitudinally disposed within the elongatedmember, the internal channel having a substantially constant diametercentral hole surrounded by the tapered elongated member along the entirelength of the internal channel with the internal channel having a closedend located at approximately the intermediate point of the elongatedmember and extending to the proximal end of the elongated member atwhich position the channel has an open end, whereby the taperedelongated member has a hollow portion for the length of the internalchannel and provides the wall for the hollow portion, wherein due to thechannel having a constant diameter but the elongated member having atapered outer shape, the thickness of the wall of the elongated membersurrounding the internal channel varies from a larger thickness at theproximal end of the elongated member to a thinner wall thickness at thechannel closed end; wherein the tapered elongated member furthercomprises a solid portion extending from the closed end of the internalchannel to the distal end of the elongated member which comprises asolid mass; a tip lead configured on the distal end of the elongatedmember, the tip lead being adapted for cutting hard tissue and havingblunt edges, a generally blunt distal tip, and at least one surfacehaving an abrasive mill-file configuration.
 18. The ultrasonic horn ofclaim 17, wherein the tip lead has a curvilinear edge.
 19. Theultrasonic horn of claim 17, wherein the solid portion of the elongatedmember has an inverse exponential profile and the proximal hollowportion of the elongated member has a Gaussian profile.
 20. Theultrasonic horn of claim 17, further including an extension member and aflared member that are disposed at the proximal end of the elongatedmember, the extension member and the flared member including anextension of the internal channel of the elongated member and configuredto interconnect with the elongated member such that the extension of theinternal channel is aligned with the internal channel of the elongatedmember, the length of the extension member selected such that theultrasonic horn is configured to operate at a target frequency of about36 kHz.